/*
 *  Copyright (c) 2011 The WebRTC project authors. All Rights Reserved.
 *
 *  Use of this source code is governed by a BSD-style license
 *  that can be found in the LICENSE file in the root of the source
 *  tree. An additional intellectual property rights grant can be found
 *  in the file PATENTS.  All contributing project authors may
 *  be found in the AUTHORS file in the root of the source tree.
 */

/*
 * This file contains the function WebRtcSpl_FilterMAFastQ12().
 * The description header can be found in signal_processing_library.h
 *
 */

#include "common_audio/signal_processing/include/signal_processing_library.h"
#include "rtc_base/sanitizer.h"

void WebRtcSpl_FilterMAFastQ12(const int16_t* in_ptr,
                               int16_t* out_ptr,
                               const int16_t* B,
                               size_t B_length,
                               size_t length) {
  size_t i, j;

  rtc_MsanCheckInitialized(B, sizeof(B[0]), B_length);
  rtc_MsanCheckInitialized(in_ptr - B_length + 1, sizeof(in_ptr[0]),
                           B_length + length - 1);

  for (i = 0; i < length; i++) {
    int32_t o = 0;

    for (j = 0; j < B_length; j++) {
      // Negative overflow is permitted here, because this is
      // auto-regressive filters, and the state for each batch run is
      // stored in the "negative" positions of the output vector.
      o += B[j] * in_ptr[(ptrdiff_t)i - (ptrdiff_t)j];
    }

    // If output is higher than 32768, saturate it. Same with negative side
    // 2^27 = 134217728, which corresponds to 32768 in Q12

    // Saturate the output
    o = WEBRTC_SPL_SAT((int32_t)134215679, o, (int32_t)-134217728);

    *out_ptr++ = (int16_t)((o + (int32_t)2048) >> 12);
  }
  return;
}
